Telephones have been in use for over a century. Over that time, the length of each telephone number, in addition to the total amount of telephone numbers, has steadily increased. As a result, callers have had to use more and longer phone numbers.
A caller will often know the name of the person she wants to reach but not his phone number. In order to determine the phone number, the caller can consult a directory or phone book, which lists people's phone numbers in order based on their names. Initially, such directories existed in paper form. Later, they became available via automated voice messaging systems (such as voicemail). Recently, directories have become electronic, such as software applications running on a computer or personal digital assistant (PDA).
While a caller can use various devices to access an electronic directory, it is most convenient if she can use her phone to access the directory. For example, the caller could use her phone to determine a person's phone number and then use the phone again to call the person or execute another desired function. What is needed is a directory that can be accessed using a phone and that is integrated with other phone functions such as Dial, Transfer, Conference, Pickup, Park, and Unpark.